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Discussion Starter · #1 ·
Hi all. I've just balanced the throttle bodies on my SV and had a few thoughts while I was doing it.

Bear in mind mine is a 2006 model year bike and there may be some detail differences to the earlier model.

Obviously getting at the ports to plug in the vac' gauge pipes is a ball-ache but at least with that done the adjustment is easy enough with the airbox in place as the screw is on the rear body and beind the airbox, videos I've seen show this on the front body so that may be one difference on the later bike.

I also though it would be a good idea for the future to add some vac' lines to the ports, blank them off and tie them up next to the airbox (or somewhere) to ease future checks, however I didn't have the necesary parts to do that this time, maybe next time.

Also, examining the setup another thought struck me. There are two electronic devices mounted on the airbox linking to each of the throttle bodies with a vacuum pipe, the take off is adjacent to the blanking plugs used for sync'ing so I'm presuming these are MAP sensors and are monitoring the same signal we do with the vac' gauges so I have two thoughts.
(I seem to remember reading that this arrangement was a modification on later models also.)

Maybe I can add a T piece to each of these lines and take my vac' signal from there, bit easier and probably less messy than going to the port. Any body tried this or have any thoughts?

Also it seems that the ECU is getting a signal of the inlet pressure for both front and rear, if a piece of diagnostic software was available it may be possible to see the values of these and use for balancing/synchronising purposes. I had a Triumph Thruxton a few years ago and there was a piece of free software that did exactly that for their bikes (easiest throttle balancing I've ever done, you could check it every day if you wanted!) does anyone know if anything similar exits for Suzuki's?
 

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Recently balanced my throttle bodies after checking and adjusting valve clearances.

Bought this Raytech Unit developed and sold in Australia great unit. Have installed extensions onto vacuum points which I cable tie to radiator overflow tube behind frame and block when not in use.

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Discussion Starter · #3 ·
Hi Muzza

I'm also thinking of installing extensions however if the devices on the airbox are MAP sensors then it would be easier to simply T into their vacuum feed as and when I want to synchronise, beats having to remove the airbox and delve around in that limited space under the TBs.

That's a nice looking unit you're using to measure the vacuum but expensive and does it work any better than a mechanical gauge? I guess it would be possible to have this hooked up while riding (on a private road of course) and check that the TBs are still balanced as the throttle opens.
 

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Discussion Starter · #5 ·
I synch my I4s with mercury sticks, but my ancient Uni-Syn made the job easy on the SV1k.



New, they're less than US$30 at Amazon:

https://www.amazon.com/Uni-Syn-Carburetor-Synchronizer-Synchronizing-Balancing/dp/B073RPZKBX

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Hi EJH

I guess that is the kind of device which is placed over the throttle body mouths? I've seen simlar devices before, there used to be one with a mechanical/dial gauge attached I've seen photo's of in some old books, I guess anything which will measure vacuum is fine. For a twin cylinder a simple U shaped piece of tube with some liquid inside and each end linked to one of the vac' ports is probably as good as anything, arguably very good as it's checking one side against the other. I may knock something up to do this next time I'm "Playing".
 

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I guess that is the kind of device which is placed over the throttle body mouths?
Yes, correct- start with one carburetor, adjust the dial-shaped restrictor to center the ball then zero the other carb(s) to match. Side-draft, down-draft no worries- the air column pivots so you can bring it to vertical. Takes about as long as it did to type this ;)

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Is this an alternative way to get the _ showing in my dash to the middle - position ?
Is that a synch or something else ?
And is there a reason we cant do a synch by eyeball (of course you have to pull the TB's off and look at the sun - I've managed to eyeball synch 200 or so carbs at this point in time being GSTwin's "Give me your tired, your poor, Your clogged up carbs yearning to breathe free" and I'll jet and synch them for you guy. I can eyeball synch them as well as a mercury gauge can. However does this do something more by doing it while running.
 

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BTW you have to remember, the eyeball method synchs the carbs - not going to comment on the precision - but the mercury sticks also take the engine vacuum - related to but not the same as compression (if your top ring is worn, but 2nd ring is good, you'd have poor compression but good vacuum - and if the wear was reversed it'd be the opposite), the flow rates (though that may be negligible at the low flow at idle). I can show you eyeball synch in a carb rack I have lying around, and if you put that on a bike and find its not synched by mercury sticks, you need to look elsewhere for problems.
But I do have a TPS sitting at _ on the SV. So any help is appreciated before I start on the eyeball method into a deep dark motor I cant see daylight through.
 

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The dash postion on the -C00 is adjusted by the TPS...... idle the bike around 1400 rpm.....and set the dash line to the middle by moving the TPS, then gently increase revs to 1750ish and the line should jump to the top.......adjust the TPS carefully to get that result.....
 
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Discussion Starter · #12 ·
Is this an alternative way to get the _ showing in my dash to the middle - position ?
Is that a synch or something else ?
These are two different things. the '-' in dealer mode is Throttle Position Sensor, TPS, setting, this is a sensor which varies its voltage output based on the rotation of the throttle shaft, the dashboard indicator is indicating whether the output is correct for the idle throttle position. This could vary with throttle synchronisation as syncing the TBs may result in an alteration in idle screw setting which may mean the throttle shaft position gets modified and changet the ouput from the TPS, probably best to re-check this after sync'ing.


Is that a synch or something else ?
And is there a reason we cant do a synch by eyeball (of course you have to pull the TB's off and look at the sun - I've managed to eyeball synch 200 or so carbs at this point in time being GSTwin's "Give me your tired, your poor, Your clogged up carbs yearning to breathe free" and I'll jet and synch them for you guy. I can eyeball synch them as well as a mercury gauge can. However does this do something more by doing it while running.
I'm assuming you mean checking that the throttle plates look to be equal? Good on you if you can, I definitely can't. Mind you we're lucky to even see the sun, especially at the moment, in the UK so I'll use that in my defence!
 

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WTF ??? I live in Charlotte NC - bring it on. But really its aimed at a GS500 - Parallel twin, but my eyesight and memory isn't that bad that I cant do a V twin.
Ha! I'm just down the road from you in Lake Park... you bring your trusty eyeball, and I'll dust off the MotionPro :ROFLMAO: (y)

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The dash postion on the -C00 is adjusted by the TPS...... idle the bike around 1400 rpm.....and set the dash line to the middle by moving the TPS, then gently increase revs to 1750ish and the line should jump to the top.......adjust the TPS carefully to get that result.....
Can I run it and rev it in dealer mode ? I also am not sure if I can get to that set screw setup with the airbox in place, or do I remove the airbox and it wont matter for the synch.

These are two different things. the '-' in dealer mode is Throttle Position Sensor, TPS, setting, this is a sensor which varies its voltage output based on the rotation of the throttle shaft, the dashboard indicator is indicating whether the output is correct for the idle throttle position. This could vary with throttle synchronisation as syncing the TBs may result in an alteration in idle screw setting which may mean the throttle shaft position gets modified and changet the ouput from the TPS, probably best to re-check this after sync'ing.




I'm assuming you mean checking that the throttle plates look to be equal? Good on you if you can, I definitely can't. Mind you we're lucky to even see the sun, especially at the moment, in the UK so I'll use that in my defence!
I can check for daylight under the butterflies and make sure they're equal by eye ball. May old school people use feeler gauges drill bits, etc etc.

Ha! I'm just down the road from you in Lake Park... you bring your trusty eyeball, and I'll dust off the MotionPro :ROFLMAO: (y)

View attachment 118003

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I'm not sure where lake park is, but like I said engine condition affects vacuum gauges. My eyesight and perception affects eyeball synch of carbs. If you have it synched by eyeball and your bike acts lumpy and out of synch feeling when you have it assembled on the bike, that = your motor is a bit lop sidedly worn. No way to reconcile the 2. But I'm happy to try.
 

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Hi Muzza

I'm also thinking of installing extensions however if the devices on the airbox are MAP sensors then it would be easier to simply T into their vacuum feed as and when I want to synchronise, beats having to remove the airbox and delve around in that limited space under the TBs.

That's a nice looking unit you're using to measure the vacuum but expensive and does it work any better than a mechanical gauge? I guess it would be possible to have this hooked up while riding (on a private road of course) and check that the TBs are still balanced as the throttle opens.
GDCobra yes not the cheapest method as everyone has pointed out but so easy and convenient. Self calibrates on power up then gives you instant feedback easily read as you adjust even for those who suffer poor vision. Great bit of tech at a price.
 

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You need to remove the airbox to effectively do the STPS adjustment....the TPS can be done with it on......
 

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Discussion Starter · #18 ·
GDCobra yes not the cheapest method as everyone has pointed out but so easy and convenient. Self calibrates on power up then gives you instant feedback easily read as you adjust even for those who suffer poor vision. Great bit of tech at a price.

I must admit it has got me thinking. I've got a plan to use a couple of MAP sensors and make up a circuit to give a comparative measurement of the output which will be zero when balanced. I may get around to it!
 

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Very fancy I'm still old school mercury :)
had a set of Motion Pro mercury for years.....started getting bubbles in the tubes, couldn't cure it....gone with dial type....safer if kids get amongst my crap too.....
 
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